Les Hinton, Rupert Murdoch, Andy Coulson and Rebekah Wade at a St Bride's service in 2005 to mark the departure of the last news organisation from Fleet Street Photograph: Graeme Robertson/Getty Images

Rupert Murdoch's News Group News­papers has paid out more than £1m to settle legal cases that threatened to reveal evidence of his journalists' repeated involvement in the use of criminal methods to get stories.

The payments secured secrecy over out-of-court settlements in three cases that threatened to expose evidence of Murdoch journalists using private investigators who illegally hacked into the mobile phone messages of numerous public ­figures as well as gaining unlawful access to confidential personal data, including tax records, social security files, bank statements and itemised phone bills. Cabinet ministers, MPs, actors and sports stars were all targets of the private investigators.

Today, the Guardian reveals details of the suppressed evidence, which may open the door to hundreds more legal actions by victims of News Group, the Murdoch company that publishes the News of the World and the Sun, as well as provoking police inquiries into reporters who were involved and the senior executives responsible for them. The evidence also poses difficult questions for:

• Conservative leader David Cameron's director of communications, Andy Coulson, who was deputy editor and then editor of the News of the World when, the suppressed evidence shows, journalists for whom he was responsible were engaging in hundreds of apparently illegal acts.

• Murdoch executives who, albeit in good faith, misled a parliamentary select committee, the Press Complaints Commission and the public.

• The Metropolitan police, which did not alert all those whose phones were targeted, and the Crown Prosecution Service, which did not pursue all possible charges against News Group personnel.

• The Press Complaints Commission, which claimed to have conducted an investigation, but failed to uncover any evidence of illegal activity.

The suppressed legal cases are linked to the jailing in January 2007 of a News of the World reporter, Clive Goodman, for hacking into the mobile phones of three royal staff, an offence under the Regulation of Investigatory Powers Act. At the time, News International said it knew of no other journalist who was involved in hacking phones and that Goodman had acted without their knowledge.

But one senior source at the Met told the Guardian that during the Goodman inquiry, officers found evidence of News Group staff using private investigators who hacked into "thousands" of mobile phones. Another source with direct knowledge of the police findings put the figure at "two or three thousand" mobiles. They suggest that MPs from all three parties and cabinet ministers, including former deputy prime minister John Prescott and former culture secretary Tessa Jowell, were among the targets.

However, a spokeswoman for Cameron said the Tory leader was "very relaxed about the story".

News International has always maintained it had no knowledge of phone hacking by anybody acting on its behalf.

Murdoch told Bloomberg news last night that he knew nothing about the payments. "If that had happened I would know about it," he said.

A private investigator who had worked for News Group, Glenn Mulcaire, was also jailed in January 2007. He admitted hacking into the phones of five other targets, including the chief ­executive of the Professional Footballers' Association, Gordon Taylor. Among the phones he hacked were those of the Lib Dem MP Simon Hughes, celebrity PR Max Clifford, model Elle MacPherson and football agent Sky Andrew. News Group denied all knowledge of the hacking, but Taylor last year sued them on the basis that they must have known about it.

In documents initially submitted to the high court, News Group executives said the company had not been involved in any way in Mulcaire's hacking of Taylor's phone. They denied keeping any recording or notes of intercepted messages. But, at the request of Taylor's lawyers, the court ordered the production of detailed evidence from Scotland Yard's inquiry in the Goodman case, and from an inquiry by the Information Commissioner's office into journalists who dishonestly obtain confidential personal records.

The Scotland Yard files included paperwork which revealed that, contrary to News Group's denial, Mulcaire had provided a recording of the messages on Taylor's phone to a News of the World journalist who had transcribed them and emailed them to a senior reporter, and that a News of the World executive had offered Mulcaire a substantial bonus for a story specifically related to the intercepted messages.

Several famous figures in football are among those whose messages were intercepted. Coulson was editing the paper at this time. He said last night: "This story relates to an alleged payment made after I left the News of the World two and half years ago. I have no knowledge whatsoever of any settlement with Gordon Taylor.

"The Mulcaire case was investigated thoroughly by the police and by the Press Complaints Commission. I took full responsibility at the time for what happened on my watch but without my knowledge and resigned."

The paperwork from the Information Commission revealed the names of 31 journalists working for the News of the World and the Sun, together with the details of government agencies, banks, phone companies and others who were conned into handing over confidential information. This is an offence under the Data Protection Act unless it is justified by public interest.

Senior editors are among those implicated. This activity occurred before the mobile phone hacking, at a time when Coulson was deputy and the editor was Rebekah Wade, now due to become chief executive of News International. The extent of their personal knowledge, if any, is not clear: the News of the World has always insisted that it would not break the law and would use subterfuge only if essential in the public interest.

Faced with this evidence, News International changed their position, started offering huge cash payments to settle the case out of court, and finally paid out £700,000 in legal costs and damages on the condition that Taylor signed a gagging clause to prevent him speaking about the case. The payment is believed to have included more than £400,000 in damages. News Group then persuaded the court to seal the file on Taylor's case to prevent all public access, even though it contained prima facie evidence of criminal activity.

The Scotland Yard paperwork also provided evidence that the News of the World had been involved with Mulcaire in his hacking of the mobile phones of at least two other football figures. They filed complaints, which were settled this year when News International paid more than £300,000 in damages and costs on condition that they signed gagging clauses.

Taylor declined to make any comment. Goodman, now out of jail, said: "My comment is not even 'no comment'." A spokesman for News International said: "News International feels it is inappropriate to comment at this time."

Last night, John Whittingdale, the Conservative MP who chairs the culture, media and sport select committee, said the revelation "raises a number of questions that we would want to put to News International".

He added: "The fact that other people beyond the royal family had their calls intercepted was well known. But we were absolutely assured by News International that none of their journalists were aware of that, that Goodman was acting alone and that Mulcaire was a rogue agent".

Asked if the committee would reopen the issue, he said: "The committee will want to discuss it very urgently. I think we will do so tomorrow morning, and if we decide that there are further questions to ask, then certainly we would summon back witnesses and ask those questions."